The present invention relates to a method for the preparation of polykis-azobenzenes or, more particularly, to a method for the preparation of polykis-azobenzenes by the photochemical reaction of a substituted or unsubstituted 1,4-diazidobenzene.
Polykis-azobenzenes or polymeric compounds of azobenzene are each an important coloring matter and represented by the general formula ##STR1## in which the subscript n is a positive integer and X, Y and Z are each a hydrogen atom, a halogen atom or a group selected from the class consisting of alkyl groups, alkoxy groups, acyl groups, carboxyl group, nitro group, amino group, azido group, cyano group and phenyl group as a substituent on the benzene ring. The method for the synthetic preparation of various kinds of derivatives thereof has been the subject matter of extensive investigations hitherto undertaken. In recent years, polykis-azobenzenes are highlighted as a liquid crystal material or an organic electroconductive material so that it is eagerly desired to develop an efficient method for the preparation of these polykis-azobenzenes.
The method for the preparation of polykis-azobenzenes known in the prior art utilizes a starting material which is a 1,4-di(substituted) derivative of benzene with a diazonium salt, nitro group, nitroso group, amino group and the like as the substituent groups. The prior art method utilizing these starting materials is industrially not advantageous because the process involves a sequence of a number of steps of unit reactions consequently with a low yield of the desired product. In particular, it is an extremely difficult matter to synthesize polykis-azobenzenes of a relatively high molecular weight having, for example, a value of 3 or larger of the subscript n in the above given general formula (I) in an industrially desirable yield.